Date: Wed, 21 Jan 98 09:18 EST From: "Michael.Chamberland" <23274MJC@MSU.EDU> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg273$foo@default> Subject: Re: Anthocyanin-free Darlingtonia
> From: "Mellard, David" <dam7@cdc.gov>
> Hi Jan and list members,
>
> Your point about combining morphology and ecology sounds logical and
> reasonable. I'm surpirsed sometimes to read that some taxonomists base
> their decisions just (or maybe I should say predominantly) on morphology
> when looking at a specimen and deciding where it fits in the taxonomic
> scheme.
This is likely true for older taxonomic work, but most contemporary
systematic studies combine other evidence (chemical, cytological, ecological)
data with the morphological data, to support a phylogeny. Because some of
the other (non-morphological) techniques require specialized equipment, you
maynot often find a paper that combines several multiple techniques in one
publication. Application of the other techniques may be another study in
itself. Look for other studies cited in the morphological papers, since the
chemical, cytological, and ecological papers may not always be well known
to hobbyists, who as a group usually favor the morphology-based articles.
I also think that plants with attractive morphology tend to generate an
abundance of morphological studies, to the risk of redundancy. I hope
nobody here is thinking of doing morphological study of pretty plants :-) :-)
> Applying your ideas mentioned above, is it right to assume that S.
> purpurea purpurea f. heterophylla is a distinct taxonomic entity because
> it predominates in some wild populations of S. purpurea purpurea?
> Whereas, in other Sarr species with the occassional anthocyanin-free
> variant in a wild population, such designations are not warranted?
I noticed Jan's statement about the distribution of Sarracenia purpurea
f. heterophylla a while back, but I was too busy to say something then.
As far as I know, the Michigan populations of this plant are the best
documented ones. From what I've seen in Michigan, both the red and
anthocyanin-lacking forms grow together in the same populations. The only
paper I've seen on the distribution of the forma heterophylla is Fred Case's
old paper in Rhodora, which also records the two forms growing together.
Are there other publications on this plant's distribution which I've
missed?
Like Jan, I also have problems with the use of the rank of forma.
Especially because forma ranking seems to usually be arbitrary. That is, a
variant plant will be named as forma usually only if the variation is a
conspicuous one in a showy plant, or one of horticultural interest. In
most cases I think these variants would be better named as cultivars
if they are grown; and if not grown, then referred to as "forms" (in the
vernacular) and not given a latin forma epithet. I could go on and on
about why forma names are bad, but I won't bore you all.
> Now, I'll add a superficial observation from my outdoor bog. The lone
> S. purp purp f. heterophylla seems to be in better shape than S. purp
> purp and S. purp venosa that are growing in the same outdoor conditions.
> The purp purp and purp venosa species have a few pitchers that are
> weathered and probably no longer functional while the f. heterophylla
> pitcher's are in perfect condition. It may be that it's in slightly
> more protected position in the bog or maybe the lack of anthocyanin
> allows the chlorophyll to be more efficient at producing energy for the
> plant.. To end up predominating in a wild population the anthocyanin
> free mutant must have some type of ecological advantange, which ends up
> being the justification for giving it taxonomic status.
Perhaps your anthocyanin-free plant has a better established root system,
or is in a better corner (micro-habitat) in your bog? Difficult to say
with a sample size of one! :-)
Michael Chamberland
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